Animals live in close association with microorganisms, carrying beneficial bacteria while coping with pathogenic infections. Now, in a study published this week in PLoS Genetics, researchers from Instituto Gulbenkian de Ciência ...

Cystic fibrosis (CF) is a genetic disorder in which chronic accumulations of thick mucus, called sputum, can trap bacteria in the lungs and cause frequent, serious lung infections. There is no cure for cystic fibrosis, but ...

Everybody knows a clean house is a healthy place to live, but what if you live on the International Space Station? Air and water are constantly recycled and waste can only be removed when a spacecraft departs for Earth every ...

An international consortium of researchers from INRA (France), University of Copenhagen and SEGES (Denmark), BGI-Shenzhen (China) and NIFES (Norway) has now established the first catalogue of bacterial genes in the gut of ...

Spores of Bacillus bacteria can survive for years in a dormant state, and then germinate in minutes. But it has long been unclear whether germination required protein synthesis, or cellular energy packets, which are known ...

Like humans, bacteria come under attack from viruses and rely on an immune system to defend themselves. A bacterial immune system known as CRISPR helps microbes "remember" the viruses they encounter and more easily fend them ...

Rust is the bane of steel, whether on cars, on ships and boats, or as part of marine infrastructure. Now, contrary to previous thinking, it turns out that the ocean-dwelling, steel-corroding species, Mariprofundus sp. DIS-1, ...

In adhering to body cells, many bacteria cause disease. Antibiotics are the usual means for treating infection, but decades of use have led to increasing bacterial resistance. Therefore, scientists are looking at other strategies.

The bacteria [bækˈtɪərɪə] (help·info) (singular: bacterium)[α] are a large group of unicellular microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals. Bacteria are ubiquitous in every habitat on Earth, growing in soil, acidic hot springs, radioactive waste, water, and deep in the Earth's crust, as well as in organic matter and the live bodies of plants and animals. There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water; in all, there are approximately five nonillion (5×1030) bacteria on Earth, forming much of the world's biomass. Bacteria are vital in recycling nutrients, with many steps in nutrient cycles depending on these organisms, such as the fixation of nitrogen from the atmosphere and putrefaction. However, most bacteria have not been characterized, and only about half of the phyla of bacteria have species that can be grown in the laboratory. The study of bacteria is known as bacteriology, a branch of microbiology.

There are approximately ten times as many bacterial cells in the human flora of bacteria as there are human cells in the body, with large numbers of bacteria on the skin and as gut flora. The vast majority of the bacteria in the body are rendered harmless by the protective effects of the immune system, and a few are beneficial. However, a few species of bacteria are pathogenic and cause infectious diseases, including cholera, syphilis, anthrax, leprosy and bubonic plague. The most common fatal bacterial diseases are respiratory infections, with tuberculosis alone killing about 2 million people a year, mostly in sub-Saharan Africa. In developed countries, antibiotics are used to treat bacterial infections and in agriculture, so antibiotic resistance is becoming common. In industry, bacteria are important in sewage treatment, the production of cheese and yoghurt through fermentation, as well as in biotechnology, and the manufacture of antibiotics and other chemicals.

Once regarded as plants constituting the class Schizomycetes, bacteria are now classified as prokaryotes. Unlike cells of animals and other eukaryotes, bacterial cells do not contain a nucleus and rarely harbour membrane-bound organelles. Although the term bacteria traditionally included all prokaryotes, the scientific classification changed after the discovery in the 1990s that prokaryotes consist of two very different groups of organisms that evolved independently from an ancient common ancestor. These evolutionary domains are called Bacteria and Archaea.